Of the worlds proven oil reserves, over half are considered heavy oil (generally defined as having an API gravity of 20 or less) and many of these are new production areas with rapidly evolving technology and new demands. One of the most challenging aspects of such heavy oil production is the transport of these highly viscous fluids. Transport of viscous fluids along pipelines for crude oil production, delivery to a refinery, or other storage facility presents a myriad of challenges. One major challenge is recovering and transporting high viscosity petroleum products from well sites to refineries or storage facilities. Transport may be hindered by multiple variables, including diffusion rates of fluids, pressure drops across flow lines, pressure limits of equipment, changing temperatures due to environment, and fluid density, to name a few. These factors and others can, for example, limit production, cause differed production, and require additional equipment due to high fatigue and failure rates. In many proven petroleum-containing sites, very little petroleum may be obtained by known means because of the high viscosity of the petroleum products.
When extracted from the subterranean formation, viscous oil must be transported from the field to a refinery or shipping terminal. Various techniques are known for aiding in the recovery of viscous petroleum and facilitating its transport to a refinery, storage site, or other location. These techniques include, for example, mechanical pumping, mechanical pumping combined with steam injection, mining, heating, and addition of low viscosity diluents (e.g., heavy aromatic naptha distillates, sometimes referred to as “HAN”). Pumping unit limitations have a negative impact on the economics of producing viscous, oil from pumped wells found in many parts of the world. The high viscosity of these crude oils results in low pump volumetric efficiency, reduced flow rates, and high flow pressure drop. Heat and steam have additional costs associated with energy input and diluents have transport and recycling costs.
Heavy oils exhibit a viscosity generally from 10,000 to 500,000 cP at room temperature. As a result, according to current practice pumping and heating stations are used to maintain a low viscosity for transport along pipelines. However, prolonged pumping interruptions often occur resulting in cold crude oil with concomitant plugging of pipes and pumps. Insulating hundreds of miles of pipe to reduce heat loss is usually cost prohibitive. Heating the crude oil likewise consumes a large amount of energy and is cost ineffective. Diluents (e.g., HAN, fuel oil, and kerosene) are sometimes used to reduce viscosity for pumping and transport. However, the large amount of diluent required is not always readily available in the production area and, furthermore, in existing practices the diluent has to be recovered at the fluid delivery site and pumped back to the field over great distances.
Current production of heavy oils from the subterranean formation to the processing facilities results in significant pressure drop, fatigue of pumping equipment, and low fluid production rates due to the high viscosity of the crude oil component of the production fluid. There thus exists an ongoing need for unproved methods to decrease the viscosity of hydrocarbons to improve pump performance and operating efficiency thereby enhancing production. There exists a specific need for enhancing recovery and transport of viscous and extremely viscous petroleum such as that found in heavy oil reservoirs and other deposits.